1. Field of the Invention
The present invention relates to a package, a method of manufacturing packages, and a method of manufacturing piezoelectric vibrators.
2. Description of the Related Art
In recent years, package products including a base substrate and a lid substrate anodically bonded to each other in a laminated state and formed with cavities formed therebetween and operating reeds mounted on the base substrate at portions positioned in the cavities are widely used. As a package product of this type, for example, a piezoelectric vibrator mounted in mobile phone sets or portable information terminal devices and using crystal or the like as a time instance source, a timing source for control signals or the like, and a reference signal source or the like, is known.
As a package in such a package product and a method of manufacturing the same, a package manufactured by laminating and bonding substrates is described, for example, in Patent Document 1. According to the package described in Patent Document 1, the interior of a space in the package can be hermetically sealed.
Also, in Patent Document 1, there is a description that metals such as aluminum, titanium, tantalum, silicon, and the like or semiconductors may be used as a bonded layer.    Patent Document 1: Japanese Patent No. 3621435
According to a package and a method of manufacturing the same described in Patent Document 1, the metals as described above or the semiconductors are used as the bonded layer, and packages are cut out along grooves formed at intermediate portions of the bonded layers in the width direction thereof. Therefore, the bonded layer is exposed from cut surfaces of the cut out packages.
However, with the package described in Patent Document 1, the bonded layer may be subject to corrosion when it comes in contact with an external environment, specifically, acid or alkali. For example, when the bonded layer is configured using aluminum having high bonding property, since aluminum oxide (alumina) in a film form is generated on the surface of the bonded layer exposed to atmospheric air normally in the atmospheric air, corrosion in the deep portion of the bonded layer is restrained. Here, in a case where atmospheric humidity is high, or in an environment in which the bonded layer comes into contact with acid solution, because of aluminum's readiness to be ionized, local battery is generated in the bonded layer, and hence the bonded layer is subjected to corrosion easily to the deep portion. If the bonded layer is subjected to corrosion, atmospheric air flows in through a gap thereof, and the interior of the package cannot be maintained in a predetermined environment any longer, thereby affecting the performance of the package product.
In order to restrict the corrosion of the bonded layer as described above, application of a coating which covers the bonded layer on an outer periphery of the package is known.
However, in order to apply such a coating, it is necessary to provide a specific step for applying a coating material. In addition, in order to ensure the coating of the bonded layer with the coating material and avoid the coating material from adhering to a portion such as an electrode, high degree of working accuracy is required.
Also, when configuring the bonded layer while assigning a priority to having a high corrosion-resistant property, an insufficient bonding property between the substrates may be resulted, and also quality maintenance of the package product may become difficult.